The seal obtainable by a closure of the said type is good and basically obtained by radially acting seal rings, possibly in combination with a sealing membrane sealing the male element and the female element against the environment.
The movement pattern for the prior art sealing device or the so-called spout is extremely simple; the elements are separated and assembled simply by axial relative movement.
The prior art closures do also have the advantage that the elements forming a part of the container closure are easily maneuverable and, in a sealed condition do maintain the sterility of a sterilizable packaging container basically up to the moment when the container is opened by separating the male and female elements.
Generally, such a separation takes place under sterile conditions, for instance by placing a filler orifice into abutment against the female element where the orifice has an arrangement for sterilizing, for instance steam sterilizing, and accomplishes sterilization of the external side of the combined arrangement of the female element and the male element before such elements are separated.
A packaging container without food contents, generally may be sterilized without breaking any regulations by using an energy rich radiation, for instance, gamma radiation. Such a sterilizing procedure gives a high quality sterile environment for the further handling of the container.
However, the regulations are such that, in general, sterilization of food products by high energy radiation is not allowed. This means that in practice it is necessary to find a partition wall or border line between a space in which radiation sterilization is acceptable and another space where such sterilization is not acceptable. In the known container structure comprising a male and a female element or a so-called spout, such partition is defined by the external side of the male element, the free circumferential edge of the female element and a seal, an O-ring, arranged between the said portions.
Such a partition forms a discontinuous surface having pronounced microorganism pockets which are not very simple to sterilize by using water vapour.